The investigations proposed would enable us to establish a sensitive and high-resolution system for the immunochemical and biochemical characterization of the cell surface and membrane antigens of Trypanosoma cruzi. Two-dimensional, crossed immunoelectrophoresis (CIE) would be used to resolve and identify the T. cruzi antigens, including exoantigens released into culture media, outer membrane surface or coat antigens and antigens of the cell cytoplasmic compartment. The CIE system also permits the identification of antigens as enzymes by zymogram staining of immunoprecipitates. This analysis will thus be both immunochemical and biochemical. Both culture and blood forms of T. cruzi will be examined for differences in exo and cell surface and membrane antigens. Lectins will be used in the CIE system for affinoelectrophoresis of antigens and identification of glycoproteins, polysaccharide and lipopolysaccharide antigens. The establishment of a high resolution system of characterizing T. cruzi antigens would then be available as a reference system for the detection of human anibodies reactive with T. cruzi by use of the CIE-intermediate gel procedure. The results of the investigations would have a direct bearing on recognition of categories of antigens to be considered for serodiagnosis and vaccine development, as well as yielding basic knowledge of the antigenic and enzymatic architecture of T. cruzi surface structures.